diff --git a/pibackup.sh b/pibackup.sh
index 40e829e..3929c9c 100755
--- a/pibackup.sh
+++ b/pibackup.sh
@@ -11,8 +11,8 @@ Password="P1backup"
 
 logfile=/opt/idssys/pibackup/logfile
 
-if grep '/dev/nvme0n1' /etc/mtab > /dev/null 2>&1; then dtype=/dev/nvme0n1
-elif grep '/dev/mmcblk0' /etc/mtab > /dev/null 2>&1; then dtype=/dev/mmcblk0
+if		[ -d /dev/nvme0n1 ];	then dtype=/dev/nvme0n1
+elif	[ -d /dev/mmcblk0 ];	then dtype=/dev/mmcblk0
 fi
 
 echo "HERE: ${dtype}"